This invention relates to a composition and method for controlling infestations of mites. More particularly, the invention relates to a synergistic blend of certain known insecticidally active components which effect such control much more efficiently, and does so with less environmental risk.
U.S. Pat. No. 3,657,451 discloses a composition that is effective in controlling mites. The composition is an organo-tin compound of the formula: ##STR1## wherein R is a lower alkyl, R' and R" are each hydrogen or lower alkyl, m is an integer from 0 to 2, n is 1 or 2, and X is a member of the group consisting of halogen, OH.sup.- and RCOO.sup.- when n is 1, and --O-- when n is 2. An embodiment of this class of compounds is sold by Shell Oil Company under the trademark "Vendex". Vendex is di[tri-(2-methyl-2-phenylpropyl)tin]-oxide, i.e., the compound set forth above where R and R' are methyl, m is 0, n is 2, and X is --O--. Upon dissolution in water, the oxide linkage is hydrolyzed to produce tri-(2-methyl-2-phenyl propyl)tin hydroxide.
Aqueous solutions of salts of certain fatty acids, primarily sodium or potassium fatty acid soaps, have recently come into use as insecticides, and have moderate effectiveness against mites. The salts are naturally occurring materials having no known long term environmental effects. Such a composition is presently sold by Safer, Inc., of Wellesley, Mass., under the trademark "Insecticidal Soap".
It was hypothesized that such fatty acid soaps might be used to extend the efficacy of organo-tin compounds as both the Vendex and the Insecticidal Soap might each retain insecticidal activity in admixture, and might form a stable complex soluton. If both materials retained efficacy in such a composition, it might be possible to reduce the amount of organo tin compound required to control mites in a given area and thus to provide an environmentally more compatible miticide.
It is an object of this invention to provide a miticide that includes an appreciable quantity of material that is not harmful to the environment and that is unexpectedly effective.
This and other objects and features of the invention will be apparent from the description and the claims that follow.